Which Has a Superior Dosimetric Profile in Image-guided High-dose-rate Brachytherapy of Cervix - Tandem Ovoid or Tandem Ring Applicator?

Abstract

Objective: This study aims to evaluate and compare the dosimetric performance of tandem ovoid (TO) and tandem ring (TR) applicators in image-guided high-dose-rate intracavitary brachytherapy for cervical cancer.

Materials and methods: Computed tomography datasets from 45 cervical cancer patients treated with either TO or TR applicators were analyzed. Dose-volume histograms were generated, and dose parameters for the target and organs at risk (OARs) were recorded for each insertion. Key dosimetric metrics, including doses to points A and B, D90 for the clinical target volume (CTV), and 2cc doses for the bladder, rectum, and sigmoid, were compared between the two applicator groups.

Results: Dosimetric outcomes for target volumes showed no significant differences between TO and TR applicators, with comparable doses to point A (P = 0.12), point B (P = 0.43), and D90 CTV (P = 0.10). Similarly, OAR doses for the bladder (P = 0.10), rectum (P = 0.15), and sigmoid (P = 0.10) were statistically equivalent. However, TR applicators consistently delivered significantly higher doses to vaginal dose points (except anterior 5 mm points), highlighting a notable difference in dose distribution patterns.

Conclusion: While both TO and TR applicators achieve similar dosimetric outcomes for the target and major OARs, the TR applicators are associated with significantly higher vaginal dose exposure. This distinction may have clinical implications, particularly for patients at risk of vaginal toxicity, and underscores the importance of applicator selection based on individual patient anatomy and treatment goals.